#!/bin/bash
# SPDX-License-Identifier: BSD-3-Clause
# Copyright (C) 2021 Intel Corporation.
#
# Script to setup mechanism for Tx queue selection based on Rx queue(s) map.
# This is done by configuring Rx queue(s) map per Tx queue via sysfs. This
# Rx queue(s) map is used during selection of Tx queue in
# data path (net/core/dev.c:get_xps_queue).
#
# typical usage is (as root):
# set_xps_rxqs <ethX>
#
# to get help:
# set_xps_rxqs

iface=$1

if [ -z "$iface" ]; then
	echo "Usage: $0 <interface>"
	exit 1
fi

CHECK() {
	if ! "$@"; then
		echo "Error in command ${1}, execution aborted, but some changes may have already been made!" >&2
		exit 1
	fi
}

CPUMASK() {
	cpu=$1
	if [ $cpu -ge 32 ]; then
		mask_fill=""
		mask_zero="00000000"
		pow=$((cpu / 32))
		for ((i = 1; i <= pow; i++)); do
			mask_fill="${mask_fill},${mask_zero}"
		done

		cpu=$((cpu - 32 * pow))
		mask_tmp=$((1 << cpu))
		mask=$(printf "%X%s" $mask_tmp $mask_fill)
	else
		mask_tmp=$((1 << cpu))
		mask=$(printf "%X" $mask_tmp)
	fi
	echo $mask
}

for i in /sys/class/net/"$iface"/queues/tx-*/xps_rxqs; do
	j=$(echo $i | cut -d'/' -f7 | cut -d'-' -f2)
	mask=$(CPUMASK $j)
	echo ${mask} > $i
	CHECK echo ${mask} > $i
done
